/*
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You under the Apache License, Version 2.0
 *  (the "License"); you may not use this file except in compliance with
 *  the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */

package org.apache.tomcat.util.collections;

import java.util.Vector;

/**
 * A simple FIFO queue class which causes the calling thread to wait if the
 * queue is empty and notifies threads that are waiting when it is not empty.
 * 
 * @author Anil V (akv@eng.sun.com)
 * 
 * @deprecated
 */
public class Queue {
	private Vector vector = new Vector();
	private boolean stopWaiting = false;
	private boolean waiting = false;

	/**
	 * Put the object into the queue.
	 * 
	 * @param object
	 *            the object to be appended to the queue.
	 */
	public synchronized void put(Object object) {
		vector.addElement(object);
		notify();
	}

	/**
	 * Break the pull(), allowing the calling thread to exit
	 */
	public synchronized void stop() {
		stopWaiting = true;
		// just a hack to stop waiting
		if (waiting)
			notify();
	}

	/**
	 * Pull the first object out of the queue. Wait if the queue is empty.
	 */
	public synchronized Object pull() {
		while (isEmpty()) {
			try {
				waiting = true;
				wait();
			} catch (InterruptedException ex) {
			}
			waiting = false;
			if (stopWaiting)
				return null;
		}
		return get();
	}

	/**
	 * Get the first object out of the queue. Return null if the queue is empty.
	 */
	public synchronized Object get() {
		Object object = peek();
		if (object != null)
			vector.removeElementAt(0);
		return object;
	}

	/**
	 * Peek to see if something is available.
	 */
	public Object peek() {
		if (isEmpty())
			return null;
		return vector.elementAt(0);
	}

	/**
	 * Is the queue empty?
	 */
	public boolean isEmpty() {
		return vector.isEmpty();
	}

	/**
	 * How many elements are there in this queue?
	 */
	public int size() {
		return vector.size();
	}
}
